1. Field of the Invention
The present invention relates to devices used in electrical therapy and, in particular, to a defibrillator for delivering artifact-compensated defibrillation pulses while cardio-pulmonary resuscitation (CPR) is being performed on a patient.
2. Description of the Related Art
Medical equipment manufacturers have developed Automated Electronic Defibrillators (AEDs) to provide early defibrillation. AEDs deliver a high-amplitude current pulse, waveform, or shock to the heart in order to restore the patient's heart rhythm to a normal level. For example, FIG. 1 depicts the conventional AED 6 being applied to a cardiac arrest victim 2 by a rescuer 4. As shown in FIG. 1, a pair of defibrillation electrodes 8 is placed on anterior-anterior (AA) positions on the victim's torso for delivering the shocks. At the same time, it is also necessary to perform a cardio-pulmonary resuscitation (CPR) on the patient while delivering the defibrillation shocks in order to revive the victim from the cardiac arrest.
In treating victims of cardiac arrest with a defibrillator, it is important that the treatment be performed very rapidly as their chances of surviving the cardiac arrest decrease drastically over time following the cardiac arrest. Thus, a quick response to cardiac arrest in administering a defibrillation shock after performing the CPR precordial compressions at the rescue scene is critical. In addition to deploying a defibrillation shock rapidly as needed to improve the resuscitation benefit, measuring accurate signals in the presence of other artifact signals, such as the movement of the victim during the CPR operation, is vital when making a correct decision with respect to a patient's treatment or, for devices that use algorithms to make decisions.
With regards to the above paragraph, there are two time intervals that are of importance, only one of which is addressed by this invention. The chance of survival decreases rapidly following the loss of circulation. Consequently the time from the beginning of the arrest until the first defibrillation shock is important. This interval is important whether or not CPR is performed, but is not addressed by this particular invention. When CPR is performed, some level of circulation is restored artificially, which can improve the chances of survival. When CPR is discontinued to allow the AED to analyze the heart rhythm (via the ECG), circulation is once again stopped. A long interval between discontinuation of CPR and shock delivery will decrease the chance of survival. It is this second interval that is addressed by this invention. Therefore, the present invention provides an improved defibrillator that is easy to use and that enables a minimally trained user to easily, rapidly, and effectively deploy the defibrillator to treat the patient, while reducing the time interval between precordial compressions and delivery of a defibrillation shock.